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Topic: AI Servo on 5Dmk2 Is it different? (Read 9218 times)

Ok on the weekend for a casual street shoot, I thought I would travel light and only take the 5D mk2 and leave the 1D3 at home and I wanted to givethe AI servo a try only shooting a walking model not exactly sport or high action, there was a decent amount of high level cloud giving a nice diffused light so it was in the ISO 100 to 200 territory (good light) only using the center point and 70-200 f2.8 or 50 f1.4 (I also use back button focus the AF-on button to focus the trigger button only meters and shoots) set AI Servo, aperture set at 2.8

Model was walking down the street towards me quite slowly and achieved focus lock with the center point waited a second or so and started shooting....

Every single shot was out of focus, I was only shooting single shot not using rapid fire

If I do the same thing with the 1Dmk3 I would guess at least 90% of the shots are crsip and in focus

Does the 5D mk2 AI servo work differently? I cant work out what i was doing wrong?Mt Spokane have you got any idea since you have the same camerasand seem to have success with the 5D2

Wait, you mean the AI Servo AF on the 5DII isn't all that great?!? (Sorry, that just slipped out...)

First, I assume you were holding down a shutter half-press or AF-ON to keep servo active?

The 5DII has 6 invisible AF assist points only for AI Servo. But, for some bizarre reason they're off by default - did you enable them (C.Fn III-7)?

LOL I know its a surprise but I at least assumed it should work to a certain degree and I figured surely a strolling model in decent light should push it to its limits. Unless they just put AI servo mode on there to tease us...

I'll check for the invisible AF setting

I also have the AF set so it is single point only on the center not that bunky automatic pick random stuff AF thing

Sounds like a settings problem, AI servo works fine with center point and moving subjects as long as its not a object going very fast. I have shot rapidly moving people with the center spot and AI servo just fine. It won't match my 1D MK III for really fast motion, but I did not expect that.

could it be recomposing the shot causing it to lose track perhaps? on the 1Dmk3 I'll begin tracking using the AF point nearer to the composition i want. Maybe I should try again but just hold the center point on the subject but that kind of defeats the purpose of using the 5d as I would then need to crop it significantly droping the resolution down to 1dmk3 levels anyway. AI servo should track to all the other points shouldn't it? As I understand it the critical part is achieving focus lock in the first place.

could it be recomposing the shot causing it to lose track perhaps? on the 1Dmk3 I'll begin tracking using the AF point nearer to the composition i want. Maybe I should try again but just hold the center point on the subject but that kind of defeats the purpose of using the 5d as I would then need to crop it significantly droping the resolution down to 1dmk3 levels anyway. AI servo should track to all the other points shouldn't it? As I understand it the critical part is achieving focus lock in the first place.

Focus and recompose using AI Servo??

The 5D MK II is not good at tracking accross the AF points. Its good on the center point, but you will not likke it if you try to track on all points.

I'm sure you know what you mean, but how does holding the center point on the subject you want cause you to crop any more than pointing it somewhere else which has subject matter that is not what you want?

could it be recomposing the shot causing it to lose track perhaps? on the 1Dmk3 I'll begin tracking using the AF point nearer to the composition i want. Maybe I should try again but just hold the center point on the subject but that kind of defeats the purpose of using the 5d as I would then need to crop it significantly droping the resolution down to 1dmk3 levels anyway. AI servo should track to all the other points shouldn't it? As I understand it the critical part is achieving focus lock in the first place.

Focus and recompose using AI Servo??

The 5D MK II is not good at tracking accross the AF points. Its good on the center point, but you will not likke it if you try to track on all points.

I'm sure you know what you mean, but how does holding the center point on the subject you want cause you to crop any more than pointing it somewhere else which has subject matter that is not what you want?

generally I dont want the models Head smack bang in the middle of the shot so I focus on the eyes then typically have to recompose the shot by dropping down so that they are better placed in the frame, this works fine for single shot when relatively stationary. So on the 1D mk3 my most used AF point will be the top left and top right outside points i hardly use the center point on that body.

The 5D2 has 2 points high up and outside that are in ok positions but they are the ones that have trouble getting a lock to begin with so i'm left with using the center point and recomposing. SO My process goes like this press the AF-on button with the centerpoint on the models eye hold for AI servo or release for single shot, adjust the frame to composition where the model is in a pleasing frame full body, 3/4 or close all involve moving to get a good composition. Then take the shot using the shutter. I have to admit i didnt pay attention to the AF dot in the viewfinder during recomposing to see if it lost tracking as i moved the camera.

JackSw1ss

sorry but from what you told here seems indeed like you were not keeping the shutter half pressed (or the AF-on pressed) all the time.Furthermore, if you'd recompose it would off course lose track of the subject because you're using the center point only.I'm speaking like this because I shoot a lot of cycling stuff (with 7D) and used a lot servo. I said used because I started getting better at focusing and I don't use servo almost anymore. just single point normal focus now.But anyway, when using servo this happened to me (that might be related to your problem):if I use servo i can either set to use one point only or a group of points. if I use a group of points it's obvious that I MUST keep the moving subject inside the "box" of points otherwise my camera wouldn't know s*** of where the subject is. If one point that's even more difficult because you have to keep your point always on the subject moving otherwise the camera wouldn't keep tracking it.

Thus I started more and more not to use the servo. I mean I use it in very specific conditions where I NEED servo. Then on other situation I prefer one point and keep focusing on my own. That's why I found nooo issue using a 5D for sports and that's why I'm buying one in the next weeks...I tried one of my friend and saw no issue on focusing.You just have to use it "correctly". It's in quote marks because my use of focus is not the real correct one. Meaning that on my 7D i use center point almost 98% of the time and get spot on result everytime. it's just knowing what you wanna do and how to do it.

So for instance in you example. if you use servo one point just remember to keep the spot always on the model and to not move (recompose) otherwise you (the cam) lose the subject. If you wanna be a bit more able to have better composition while using servo you have to use the box with all the AF points, but this options can bring you to lots of collateral troubles, like camera not focusing on what you really want, or just hitting once and then not hitting the focus (happens to my 7D too, so it's not a 5D problem only).Either way I personally would use the single point focus and not servo and try to be fast focusing the subject coming at me. I do it for object coming directly in front of me, side, and also panning....for panning I only use one point af and no servo most of the time and get say 90% great-keeper result. It's just practice.

Hope it helped

cheers

« Last Edit: November 28, 2011, 03:17:17 AM by JackSw1ss »

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JackSw1ss

.....SO My process goes like this press the AF-on button with the centerpoint on the models eye hold for AI servo or release for single shot, adjust the frame to composition where the model is in a pleasing frame full body, 3/4 or close all involve moving to get a good composition. Then take the shot using the shutter.....

Here's what I'm talkin about...u cannot use a center point only and recompose with it because the only center point will lose (track of) your subject....it will start "lookin" for what u are focusing after recomposing, it won't read your subject of before therefore won't keep track of it, if that make any sense to you. that leads to miss focus, for sure.if you wanna do that you have to use all the 9 points (though servo on 5 is better with center only) or use one point only but remembering to keep that point spot onto your subject which is moving and following it/him/her

Have you calibrated the 70-200 to the 5d? You said that your focus was always behind. I sure agree with what's being said about Ai Servo and recompose, that doesn't work, unless you pause AF (which is what I have my AF-ON button set to do) but then it obvioulsy won't track the subject. But also things need to be calibrated. I got a MUCH more stable AF when both my camera and lenses were calibrated. And it's either dead on or way off (user error)

On my old 30D I used AI Servo a great deal for motorsports (F1, MotoGP, BSB etc) with a very high success rate, but I would never have dreamt of trying to recompose the shot as I can only imagine how this would confuse the camera.

Thats one very good reason for the high MP. So I have more room to crop to a composition that works for me.

willrobb

I haven't calibrated my 70-200mm f2.8L to my 5DmkII or enabled anything via custom functions, but I shoot runway in AI servo and get good results all the time....hmm, wonder what it is? I do keep keep pressing my finger on the shutter release halfway all the time to keep refocusing, but you're doing that as well right?